Jim:--Use M.R.(green board or Blue Board) to shim out the wall, and extend the wonder board down over the tile lip of the tub, and set your tile. It is important to assure that no water draining down the walls can get behind the tile at the point where the tile meets the tub.Lots of luck with your project...Bud.

I am installing a Hydro Swirl bath tub (Whidbey #6036) that has sheetrock flanges attached. The roughin length is 59 3/4" and I have 60 3/4 wall stud to wall stud. The install diagram shows the wall board going over the flanges vs behind. QUESTION: Can I sheet rock the ends then install the tub and then cover the flanges with tile board which I will tile over?